Believed introduced in 1936 and in two designs. The double reflector was developed
after experiments in Bournemout Road, Poole. It quickly became popular for the lighting of arterial
roads and new housing estates in the same year. It consists essentially of twin-burners at the foot of paraboloid facetted Staybrite Steel reflectors,
which are positioned back-to-back. It was designed to meet the requirements of the
MOT's Interim Report, for 18' mounting height, and
for central or staggered lighting schemes. Supplied with an even number of mantles from 4 to 12.
It embodies a twin burner of unique patented construction, such that the gas enters an
annulus surrounding the mixing chamber, passes vertically downwards to the nipple, and
thence upwards, drawing in air from the body of the lamp, the gas and air regulation being
effected through the hinged door at the base of the lamp. Each burner is at the focus of a
faceted Staybrite steel reflector of paraboloid form. Candle powers of 2000 for the
six-light lamp and 3000 for the twelve-light lamp are obtained.
The reflectors are of the dispersive type and are designed to secure evenness of illumination over the carrigeway,
rather than a high concentration of candle power in one direction. The patented burner possesses certain interesting
features. The gas passes downwards through an annulus to the nipple, and thence upwards into the mixing chamber, drawing
in air from the body of the lamp. This ensures efficient combustion and also obviates the necessity for an elaborate
ventilating device to prevent the possibility of contamination of the primary air by products of combustion. Moreover, with
a bottom door, regulation of the gas and air, replacement of the mantles and cleaning, can all be effected from
the base, very important maintenance considerations.
With staggered spacings of 150 feet and for roads of normal width, Class F and E
illumination is obtained with the six-light and twelve-light lamps respectively. Mounting
heights of 18 to 25 feet for the six-light and 21 to 25 feet for the twelve-light lamp
are recommended. The lantern is ususally advertised as achieving a Class F illumination with
staggered spacing of 150 feet and a mounting height of 18 to 25 feet.
The reflectors may be set to any reasonable predetermined vertical and azimuthal angle,
and are generally adjusted to throw the maximum beam at an azimuthal angle of 10° into
the road for staggered systems, and 0° azimuth for central suspension.
The burners and reflectors are housed in a lantern of square cross section, slightly tapering towards the base,
and fitted with pyramidal roof and base. From two to sixteen mantles can be housed in the same lantern, a valuable asset
when conversions to higher power units are required by increase in traffic and greater necessity for a higher
degree of illumination.
Has a maximum candle power of 2000 with a total gas consumption of 15 cubic feet per hour.
The two 56-facet Paraboloid Metal Adjustable Refectors are of the dispersive type. The case is of modern design, square
in plan, and tapered from the waist downwards. Gas and air regulator is housed in the body of the lamp and
free from contamination of the primary air by products of combustion. Provides a good Class F Illumination for roads of
normal width. Often shown advertised on Adastra Sectional Steel Columns. Later described as
a Group "A" lantern. Is extensively installed, and is ideal for competitive schemes being highly efficient,
soundly constructed and low priced.
Redesigned in 1945, it's intended for use in Group A roads at a mounting height of 25'. It houses 6-12 mantles and
can be arranged for both suspension or upright mounting. Reflectors
can be adjusted horizontally and vertically for even spread of illumination. This adjustability
permits the most effective distribution of light for variations in the
configuration of the road including bends, gradients and varying road widths.